This time is Pandora's Box a Aluminium Tube.
I use the NIKON M Plan, 60/0.7 LWD, 210/0, with 60:1, Sharpness depth 1.1µm.
The picture width amounts 0.39mm.
These were 427 pictures, stack with Zerene.
The steps are 0.25 µm.

To clarify... It looks like you're using a "sharpness depth" that is measured as maximum deviation from the point of sharpest focus. The total DOF is twice as much. The formula for total DOF is lambda/NA^2, which for green light at lambda=550nm would be 1.12 µm. Because this subject has a lot of blue in it, we might use lambda=450nm to give a tighter estimate of 0.92 µm.

In either case, your steps of 0.25 µm are certainly small enough to avoid focus banding.